It is known that greater and greater use is being made of plastic or elastomer side elements at the ends of automobile bumpers, which elements wrap around the fenders of the car body and frequently fit in below the lower edges of the fenders. Since the rearward ends of these elements are generally attached to the chassis or to another part of the vehicle, deformation of the principal bumper toward the rear, under the influence of an impact, causes such side elements to buckle. Practice shows that, in view of the shape of these elements, and the rather variable inertia of their component elements, the effect of the buckling is to fold the edges in contact with the corresponding lower edges of the fenders, thus deforming the latter.